The subject invention relates generally to combustors. More particularly, the subject invention relates to the introduction of diluent flow into a combustor.
Combustors typically include one or more fuel nozzles that introduce a fuel or a mixture of fuel and air to a combustion chamber where it is ignited. In some combustors, the fuel nozzles extend through holes disposed in a baffle plate of the combustor. In these combustors, it is often advantageous to introduce a volume of diluent, often nitrogen or steam, to the combustor to reduce NOx and/or CO emissions and/or augment output of the combustor. The diluent is urged from a chamber through a gap between the baffle plate and each fuel nozzle then flows along a periphery of the fuel nozzle where a portion of the diluent enters a plurality of air swirler holes and is mixed with air and introduced into the fuel nozzle. Under some conditions, however, the diluent is drawn toward a center hub of the combustor, away from the plurality of air swirler holes, by, for example, a region of low pressure near the center hub. When the diluent is drawn toward the center hub, the diluent effectiveness is reduced and may cause operability problems in the combustor such as blow out.